Environmental contributions to cancer mortality will be estimated based on a proposed model using age-specific cancer death rates by cancer site. Background age-specific cancer rates by site will be estimated using NCI data on cancer mortality among U.S. counties. Various methods for estimating these background rates will be explored. Occupational cancer mortality will be estimated by comparing U.S. death rates for white males and white females. Various adjustments will be compared for sex-linked cancers and different smoking patterns.